Tire manufacture



y 2, 1945. A F. LARABEE 2,376,494

TIRE MANUFACTURE Filed Dec. 8, 1941 '2 Sheets-Sheet 1 INVENTOR :o M MM J A. F. LARABEE TIRE MANUFACTURE' May 22, 1945 Filed Dec. 8, 1941 2 Sheets-Sheet 2 VA /A/A/////////////////// IIIL V I NVENTOR .ZZZ.

Patented May 22, 1945 UNITED STATES PATENT OFFICE I TIRE; MANUFACTURE Albert F. Larabee, Jeannette, Pa., assignor to Pennsylvania Rubber Oompany, Borough of Jeannette, Pa., a corporation of Pennsylvania Application December 8, 1941, Serial No. 422,125 I 1 Claim. (01. 154-9) This invention relates to the manufacture of pneumatic tires forvehicles, and specifically to the manufacture of drum-built tires. l

In accordance with a prevailing practice, the tread and outer side walls of the outer shoe of a pneumatic tire (commonly termed, par excellence, atire) are formed from a'strip of raw rubber which, shaped to proper cross-section, is produced in relatively great and indefinite length.

A11 pp opriate shorter length cut fromthe strip 10 is applied to, shaped to, and vulcanized into union with a fabric carcass to form the completed tire.

The rubber of which the tread portion of the tire is formed is desirably a relatively hard, wear- .enduring rubber; while in the side walls of the tire the rubber is preferably of softer and more elastic character. tomary to form the strip mentioned above as a compound stripincluding two portions ofdifferently compounded material. Themedial, relatively narrow and thick body portion of the strip-the portion that ultimately forms the tread of the finished tireis made of different composition than the marginal portions of the strip that in the finished the side walls.

In Letters Patent No. 2,230,072, granted J anuary28, 1941, on thehapplication of Archibald C. Bowers, and in Letters Patent No. 2,218,751,

granted October 22, 1940, on my own application, 3

machinery is shown and describedfor shaping from two separate batches of rubber (differently compounded). the two strip parts, and for uniting them into a compound. strip. It is with the uniting means that my present invention has i to do.

The object of invention is a union of such strip parts that shall be superior in intimacy and durability.

In the accompanying drawing Fig. I is a diagrammatic View in side elevation of a machine for uniting the preformed components of the strip in contemplation, in which machine the present invention is embodied; Fig. II is a fragmentary view of the machine in plan from above; Fig. III is a view to larger scale, showing the machine in vertical and transverse section, on the plane indicated at III-III, Fig. I; Fig. IV is a view in vertical and transverse section, on the plane indicated at IV-IV, Fig. I.

Two preformed components a and b of the 50 of still unvulcanized and plastic rubber mixes On such account it is cusi tire provide the facing of1.25v

been shaped and prepared by suitable apparatus-typically by apparatus such as that described in the LettersPatent named above. Fig. II shows the assembly in plan, and Fig. III shows the strip. as unionofits components is being effected. To this figure corresponding letters a and b have been applied, and this showing will suffice to indicate that, the component b is relatively Wide and the component a relatively narnow. I It may be understood that itisthe component a which eventually constitutes the tread portion of the tire and that it is of a composition such as. to afiord when vulcanized a relatively tough and wear-resistant portion; and it is the component b which in its lateral extensions forms the faces of the side walls of the tire and that is of a composition such as to, afiord. a relativelysoft andpliant portion. The

two parts a and 1), brought beneath roller 8 to the centrally aligned and superposed positions sufficiently indicated in Figs. II and III, advance The rolls 30, 3| and ,the disks 32, 33 alike are conveniently formed of steel, and are for all present purposes to be regarded as individually rigid and unyielding bodies.

bearings; the disks 32, 33 that make .up' the compound upper roll members are, disk by disk, severally mounted to turn idly in'forks 34 that extend from the lower ends of vertically extendingand vertically movable stems 35. a

A frame 36 is provided, bridging the pathof advance of the work, and in this frame is formed a vertically extending slideway 31. A carriage is movable vertically in this slideway. It consists of two cross-heads 38 and 39 rigidly united by bolts 40 and spacer sleeves M. The carriage is rigidly borne by the stem 42 that extends vertically downward from a piston within a power cylinder 43 rigidly mounted in frame 33.

Through orifices in the cross-heads 38 and 39 the disk-carrying stems 35 extend, and the stems are free to move vertically'withinthe orifices. Rotative movement is prevented, conveniently by giving to the orifices in cross-head 39 rectangular shape, and by giving corresponding shape to of distinct and suitable composition, and have 56 the stems 35 throughout so much of their length The unitary, nether rolls 30, 3| are mounted to turn idly in stationary as makes engagement in these orifices.

Springs M yieldingly hold the stems 35 severally in downwardly extended position from the carriage, and

- enlargements upon the stems, conveniently in the form of adjustable, nuts 45 engaging the upper cross-head 38 from above, limit the stems 35 severally in their range of downward extension. The disks 32, 33 of each set are; mounted :in nor- 'mally co-axial'assembly; and from downward extended position the disks severally will under 7 stress recede vertically upward within the downwardly advanced carriage, and in their recession will, by virtue of their spring backing, exert pressure. That is to say,.the ro1l-..pass,'defined below by the roll 30, 3!, is defined above by. a succession of spaced apart, individually yielding; spring-backed disks 32, 33.

The interval at which the disks of each set are spaced apart is constant and is slightly less than the breadth of the disks, which also is constant. In a particular machine built to, meet actual conditions of production-the barrel of roll 30 is 25 inches long and 3 inches in diameter; and the disks 32, 33 are 3 inches in diameterand 0.375

0f an inch broad. Theirfaces are curved on a three-quarter-inch radiusand the-corners are rounded. Th spacing between the-disks of each set (centre plane to centre plane) *is 6 (:05688) of an inch which distance, it wiIl be seen, is

slightly less than twice the widthof the individual disk. The disks of the two sets are so arranged that the disks 33 of the second set come to bearing on the work, as itadvances through the roll passes in the right-to-left course indicated, along paths that are intermediate between the paths of bearing ofthe disks 32 of the first set; and, becauseof the slight'excess of disk width over the interval between disks, the paths of bearing of the disks of the two sets upon the work "overlap slightly at the margins.

Referring particularly to Fig. III, the portion b of the assembled blank advancing through the "roll pass is shown to be engaged from beneath by' thelcontinuous face of roll 30, while "the 'por- 7 tion a is engaged from above by the set of disks 32. It will be understood that, by proper adjust- -desired um'on. Manifestly such a set of disks lend itself to irregularity of work and effects minute distribution of the uniting stress, as an integral roll extending across the breadth of the work could not do. The set of disks is of such" "the two roll passes inI'staggeredrelaitive positions (the disks being wider, slightly,.than the intervals between disks), the upper surface of the portion a of the blank is, in the advance through the two roll passes, compressed over its entire extent. @No "pocketed or intercalated air is carried through the :roll passes; the union of the 7 -rneetingfaces of the two portions of plastic, tacky,

still incompletely vulcanized rubber is continuous and adequate; so that in the ultimately shaped and vulcanized tire the tread portion is integrated with the body of the tire in a union that is continuous and free of flaw or inequality.

disks 33, and in these two roll passes the integration-of the components is completed throughout substantially-all the breadth of portion a.

The blank in its continued advanceis subjected to the action of the pair of stitching rolls, that are arranged and that serve in the manner shown and'described inthe Bowers patent named above:

they shape the very edge of the portion a overthe ridges that are formed in'blank b, between which ridges the portion a has been "applied; and they carry to the very edge the compressive stress under which the portions a and 'b are united. Comparison of Figs. III and IV will make plain the successive action of disks 32, 33, and l l, and the efiect thereof.

'I claim as my invention:

'In rubber-fabricating machinery, means for uniting superposed layers of plastic and adhesive rubber composition, including two roll passes arranged for the successive reception of advancing work, each pass defined by and between a roll upon one side having a continuous surface and a succession of spaced apart and individually yieldable disks upon the other side, the disks being of a width exceeding the intervals at which they are spaced apart, and the disks of the-second r011 pass being centered in assembly in the spaces between the disks of the first roll pass.

ALBERT F. LARABEE. 

